package com.leet.twopoint;

public class MergeOrderedList {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode head = new ListNode(-1);
        ListNode pre = head;
        while(l1!=null && l2!=null){
            if(l1.val <= l2.val){
                pre.next = l1;
                l1 = l1.next;
                pre = pre.next;
            }else{
                pre.next = l2;
                l2 = l2.next;
                pre = pre.next;
            }
        }
        if(l1 != null) pre.next = l1;
        if(l2 != null) pre.next = l2;
        return head.next;
    }
}
